Delbrück scattering of 30–100 MeV photons by Pb through angles of 15°–30°

Elastic (Compton) scattering of 30–100 MeV protons by Pb through angles of 15°–30° is measured using the MPI tagged-photon facility at MAMI A. The data are discussed in terms of three different approaches to Delbrück scattering, viz. the lowest-order Born approximation, the small-angle high-energy approximation, and the large-angle high-energy approximation. The latter method which is investigated in detail for the first time, leads to a good agreement with experiment at Θ = 20° but to some disagreement at Θ = 15°.